Method for optimizing parameter of information storage apparatus

ABSTRACT

A method is used for optimizing a parameter of an processing unit. The method is for providing an initial input F i=0  to be a value of the parameter, and detecting a corresponding initial output O(F i=0 ), determining step value ΔF, providing a first input F 0 −ΔF and a second input F 0 +ΔF, detecting a first output O(F 0 −ΔF) and a second output O(F 0 +ΔF), determining whether the first output O(F 0 −ΔF) is greater than the second output O(F 0 +ΔF), determining a first seeking direction, providing other inputs F i , F i+1 , F i+2 , . . . F i+n−1 , and then detecting corresponding other outputs O(F i ), O(F i+1 ), O(F i+2 ), . . . O(F i+n−1 ), wherein n is a natural number, determining a stop point F i , stopping seeking along the first seeking direction at the stop point, identifying an extremum output, and identifying an input to be the optimized value of the parameter. An information storage apparatus for optimizing a parameter is also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to information storage apparatuses and, moreparticularly, to a method for optimizing parameters of an informationstorage apparatus.

2. Description of Related Art

Information storage apparatuses, such as video compact disc (VCD)players and digital versatile disc (DVD) players, are widely used forreproducing information from and/or recording information onto discs. Ageneral information storage apparatus includes a plurality of processingunits for processing a plurality of tasks. For example, a light sourceexecutes a projection of a light beam, and a detector executes adetection of a reflected light beam. Usually, each processing unit isassigned at least one adjustable parameter that is used for adjusting aperformance of the information storage apparatus.

Therefore, it is important to determine values of the parameters of eachprocessing unit. A conventional determining method includes followingsteps: providing various value groups to the parameters and detectingvarious output signals of an processing unit corresponding to thevarious value groups; comparing the output signals to select at leastone output signal therefrom which reflect a best performance of aninformation storage apparatus; identifying the value groupscorresponding to the selected output signals to be optimal values of theparameters. However, this determining method is time-consuming and in alow efficiency.

Therefore, an improvement of a method for optimizing the parameter of aninformation storage apparatus is desired.

SUMMARY OF THE INVENTION

A method is used for optimizing a parameter of an processing unit. Themethod is for providing an initial input F_(i=0) to be a value of theparameter, and detecting a corresponding initial output O(F_(i=0)),determining step value ΔF, providing a first input F₀−ΔF and a secondinput F₀+ΔF, detecting a first output O(F₀−ΔF) and a second outputO(F₀+ΔF), determining whether the first output O(F₀−ΔF) is greater thanthe second output O(F₀+ΔF), determining a first seeking direction,providing other inputs F_(i), F_(i+1), F_(i+2), . . . F_(i+n−1), andthen detecting corresponding other outputs O(F_(i)), O(F_(i+1)),O(F_(i+2)), . . . O(F_(i+n−1)), wherein n is a natural number,determining a stop point F_(i), stopping seeking along the first seekingdirection at the stop point, identifying an extremum output, andidentifying an input to be the optimized value of the parameter. Aninformation storage apparatus for optimizing a parameter is alsodisclosed.

Other advantages and novel features will become more apparent from thefollowing detailed description of preferred embodiments when taken inconjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the method of optimizing an parameter and theinformation storage apparatus using the method can be better understoodwith reference to the following drawings. The components in the drawingsare not necessarily to scale, the emphasis instead being placed uponclearly illustrating the principles of the present disc drive. Moreover,in the drawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a block diagram of an processing system;

FIG. 2 is a block diagram of a typical information storage apparatus;

FIG. 3 is schematic diagram of an exemplary graph illustratingrelationships between inputs and outputs;

FIG. 4 is a flow chart illustrating an method for optimizing anparameter in accordance with an first exemplary embodiment; and

FIG. 5 is schematic diagram of exemplary graph illustrating threeminimum O(F_(i))s.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made to the drawings to describe the preferredembodiments of the present method of determining an optimal parameterand the present information storage apparatus, in detail.

Referring to FIG. 1, a schematic block diagram of a processing system isillustrated. The processing system includes an processing unit 22assigned with at least one parameter, and a parameter-adjusting unit 20for adjusting values of the at least one parameter of the processingunit 22.

Referring to FIG. 2, an information storage apparatus 2 acts as anembodiment of the processing system, and an optical pick-up head 22 actsas an embodiment of the processing unit in the information storageapparatus 2. The optical pick-up head 22 projects a light beam to a disk10 to form a spot 222 on the disk 10 and receives a reflected light beamfrom the disk 10. A plurality of adjustable parameters is preconfiguredin the optical pick-up head 22. The information storage apparatus 2further includes a parameter-adjusting unit 20 for adjusting values ofthe parameters of the optical pick-up head 22, thus improving aperformance of the information storage apparatus 2. For example, anFbias (focus equalizer bias voltage) parameter is assigned to theoptical pick-up head 22, a value of which represents a deviation of afocus 220 of the light beam away from the spot 222 in a perpendiculardirection relative to the disk 10. The deviation of the focus 220affects qualities of reproduced or recorded information.

Therefore, it is important to identify optimal values of the parametersof each processing unit 22. The processing unit 22 has optimal outputsaccording to the optimal values of the parameters. A method to identifyat least one optimal value of a parameter includes the following steps:providing a series of inputs F_(i); detecting a series of outputsO(F_(i)) of a processing unit corresponding to the inputs F_(i);identifying an extremum from the series of the outputs O(F_(i));identifying at least one input F_(i) which corresponds to the extremumof the series of the outputs O(F_(i)) to be the optimal value of thecorresponding parameter. Wherein “i” is an index identifier.

Referring to FIG. 3, an exemplary graph illustrating relationshipsbetween the inputs F_(i) and the outputs O(F_(i)). An initial input F₀is predetermined on the X-axis. A first input F₀−ΔF and a second inputF₀+ΔF are located on two sides of the F₀. A first output O(F₀−ΔF) and asecond output O(F₀+ΔF) are determined. A seeking direction is defined bya comparison result between the two outputs O(F₀−ΔF) and O(F₀+ΔF). Forexample, if a minimum deviation, i.e. a minimum value of the output ofthe processing unit, is wanted, and the comparison result shows thesecond output O(F₀+ΔF) is less than the first output O(F₀−ΔF), theseeking direction is a forward direction on the X-axis. On the otherhand, if the minimum deviation is wanted and the comparison result showsthat the second output O(F₀+ΔF) is greater than the first outputO(F₀−ΔF), the seeking direction is a backward direction on the X-axis. Aseries of other inputs F_(i)s, such as F₀+2ΔF and F₀+3ΔF, are providedalong the seek direction, so as to detect a series of correspondingoutputs O(F_(i))s. Such a seeking operation continues until the inputF_(i) satisfies a relationship ofO(F_(i))<O(F_(i+1))<O(F_(i+2))<O(F_(i+3)), an optimal output with awanted extremum is then obtained by comparing the outputs O(F_(i))s.Thereby, at least one optimal input that corresponds to the output withthe extremum is identified as the optimal values of the parameter.

Referring to FIG. 4, a flow chart showing a seeking procedure of amethod for identifying at least one optimal input F_(p) corresponding toan output O(F_(p)) having a minimum value for the processing unit 22 inaccordance with a first exemplary embodiment is illustrated. The seekingprocedure can be performed by a program stored in theparameter-adjusting unit 20.

Step 300, an initial input F₀ is provided to the processing unit 22 andan output O(F₀) is computed correspondingly.

Step 302, the value of the step ΔF is determined.

Step 303, two other inputs F₀−ΔF and F₀+ΔF are provided to theprocessing unit 22, and two other output O(F₀−ΔF) and O(F₀+ΔF) aredetected.

Sep 304, a conclusion whether the O(F₀−ΔF) is greater than O(F₀+ΔF) ismade.

If the conclusion indicates that the first output O(F₀−ΔF) is equal tothe second output O(F₀+ΔF), the procedure returns to step 302 to resetthe step value ΔF.

Step 306, if the conclusion shows that the first output O(F₀−ΔF) isgreater than the second output O(F₀+ΔF), a first seeking direction (e.g.an increasing direction of F₀) is defined as a seek direction, and i isincreased by 1.

After that, in step 308, a series of successive inputs F_(i), F_(i+1),F_(i+2), F_(i+3) are fed to the processing unit 22, and correspondingoutputs O(F_(i)), O(F_(i+1)), O(F_(i+2)), and O(F_(i+3)) are detected.

Subsequently, step 310, a determination whether F_(i) is a stop point ismade by comparing values of the outputs O(F_(i)), O(F_(i+1)),O(F_(i+2)), and O(F_(i+3)). That is, if F_(i) satisfies the relationshipof O(F_(i))<O(F_(i+1))<O(F_(i+2))<O(F_(i+3)), the F_(i) is identified asthe stop point.

If the F_(i) concluded in step 310 is not the stop point, the proceduregoes back to step 306 where i is increased by 1. If the F_(i) concludedin step 310 is the stop point, the procedure proceeds to step 312 wherethe seeking procedure is stopped.

After the seeking procedure, step 314, a determination whether F₀ is thestop point is made. If F₀ satisfies relationship ofO(F₀)<O(f₁)<O(f₂)<O(f₃), F₀ is identified as the stop point.

Step 316, if F₀ concluded in step 314 is not the stop point, the optimalinput F_(p) is determined. At least one minimum O(F_(i)) is determinedby comparing the O(F_(i))s detected in step 308. The minimum O(F_(i))swhich have a same minimum value are identified as O(F_(ij)), wherein jis an integer representing the number of the minimum O(F_(i)). Theinputs corresponding to the O(F_(ij)) are then identified as F_(ij).Then, an average of Max(F_(ij)) and Min(F_(ij)) is identified to be theoptimal input F_(p). If only one minimum O(F_(i)) is obtained, j equalsto 1, and F_(p) satisfies an equation ofF_(p)=(Max(F_(ij))+Min(F_(ij)))/2=(F_(i1)+F_(i1))/2=F_(i1). If two ormore minimum O(F_(i))s are obtained, there are a maximum F_(ij)(Max(F_(ij))) and a minimum F_(ij) (Min(F_(ij))) corresponding to theminimum O(F_(i))s, and the F_(p) satisfies an equation ofF_(p)=(Max(F_(ij))+Min(F_(ij)))/2. For instance, referring to FIG. 5,three minimum O(F_(i))s are obtained. F_(m1), F_(m2), and F_(m3) arecorresponding to the minimum O(F_(i))s, wherein F_(m1)<F_(m2)<F_(m3).Thus, the F_(p) satisfies an equation of F_(p)=(F_(m1)+F_(m3))/2.

Step 318, if F₀ concluded in step 314 is the stop point, a determinationwhether seeking procedure towards a second seeking direction, oppositeto the first seeking direction, from the initial input F₀ have been doneis made.

Step 320, if the determination in step 318 shows that the seekingprocedure towards the second seeking direction have been done, theoptimal input F_(p) is determined to be F₀.

Step 322, if the determination in step 318 shows that the seekingprocedure towards the second seeking direction have not been done, i isreset to a value of zero, and then the procedure jumps to step 324 wherei is decreased by 1.

Step 324, if the conclusion shows that the first output O(F₀−ΔF) is lessthan the second output O(F₀+ΔF), the seek direction along the secondseeking direction is started and i is increased by 1.

Step 326, a similar seeking operation is executed as step 308 along thesecond seeking direction.

Step 328, a determination is made by a same operation which is executedas step 310.

If the F_(i) concluded in step 328 is not the stop point, the proceduregoes back to step 324 where i is increased by 1. If the F_(i) concludedin step 328 is the stop point, the procedure proceeds to step 330 wherethe seeking procedure is stopped.

After the seeking procedure, step 332, a determination whether F₀ is thestop point is made. In step 332, if F₀ satisfies relationship ofO(F₀)<O(f₁)<O(f₂)<O(f₃), the F₀ is identified as the stop point.

If the F₀ concluded in step 332 is not the stop point, the optimal inputF_(p) is determined (step 316). At least one minimum O(F_(i)) isdetermined by comparing the O(F_(i))s recorded in step 326. The at leastone minimum O(F_(i)) is identified as O(F_(ij))s, wherein j is aninteger representing the number of the minimum O(F_(i)) and is not lessthan 1. Then, corresponding to the at least one O(F_(ij)), at least oneinput F_(ij) are determined, and the F_(p) satisfies an equation ofF_(p)=(Max(F_(ij))+Min(F_(ij)))/2.

Step 334, if the F₀ concluded in step 332 is the stop point, adetermination whether the seeking procedure towards the first seekingdirection have been done is made.

Step 336, if it is concluded in step 334 that the seeking proceduretowards the first seeking direction has not been done, i is reset to avalue of zero, and then the procedure jumps to step 306 where i isincreased by 1.

Step 316, if it is concluded in step 334 that the seeking proceduretowards the first seeking direction has been done, the optimal inputF_(p) is determined. In this instance, the F₀ is identified as theoptimal input F_(p).

In a second exemplary embodiment, a seeking procedure of a method canidentifying an optimal input F_(p) corresponding to a maximum output forthe processing unit 22. The difference between the first exemplaryembodiment and the second exemplary embodiment is described as follows.

When seeking the optimal input F_(p) corresponding to the maximum outputO(F_(i)), a conclusion whether the O(F₀−ΔF) is greater than O(F₀+ΔF) ismade. If the first output O(F₀−ΔF) is concluded to be greater than thesecond output O(F₀+ΔF), the procedure proceeds to step 324 where theseeking procedure is performed towards the second seeking direction. Ifthe determination shows that the first output O(F₀−ΔF) is less than thesecond output O(F₀+ΔF), the procedure proceeds to step 306 where theseeking procedure is performed towards the first seeking direction.

When determining whether F_(i) is a stop point, O(F_(i)), O(F_(i+1)),O(F_(i+2)), and O(F_(i+3)) are compared with each other in step 310 orstep 328. If the F_(i) satisfies relationship ofO(F_(i))>O(F_(i+1))>O(F_(i+2))>O(F_(i+3)) in step 310 or step 328, theF_(i) is one stop point.

In the first and the second embodiments, four inputs are fed to theprocessing unit 22 and four corresponding outputs are recorded. Inanother embodiment, the number of inputs can be another natural number.

The embodiments described herein are merely illustrative of theprinciples of the present invention. Other arrangements and advantagesmay be devised by those skilled in the art without departing from thespirit and scope of the present invention. Accordingly, the presentinvention should be deemed not to be limited to the above detaileddescription, but rather by the spirit and scope of the claims thatfollow, and their equivalents.

1. A method for optimizing a parameter of a processing unit of aninformation storage apparatus, the method comprising steps of: providingan initial input F_(i=0) to be a value of the parameter, and detecting acorresponding initial output O(F_(i=0)) of the processing unit;determining step value ΔF; providing a first input F₀−ΔF and a secondinput F₀+ΔF to be values of the parameter, and detecting a first outputO(F₀−ΔF) and a second output O(F₀+ΔF) of the processing unit;determining whether the first output O(F₀−ΔF) is greater than the secondoutput O(F₀+ΔF); determining a first seeking direction based on thedetermination; providing other inputs F_(i), F_(i+1), F_(i+2), . . .F_(i+n−1) to be values of the parameters, and then detectingcorresponding other outputs O(F_(i)), O(F_(i+1)), O(F_(i+2)), . . .O(F_(i+n−1)); wherein n is a natural number; determining a stop pointF_(i) by comparing the outputs O(F_(i)), O(F_(i+1)), O(F_(i+2)), . . .O(F_(i+n−)); stopping seeking along the first seeking direction at thestop point; identifying an extremum output based on the detectedoutputs; and identifying an input corresponding to the extremum outputto be the optimized value of the parameter.
 2. The method as claimed inclaim 1, further comprising steps of: making a determination whetherseeking procedure towards a second seeking direction being opposite tothe first seeking direction from the initial input F₀ have been done ifF₀ is a stop point; and resetting i to a value of zero, and seekingalong the second seeking direction if the seeking procedure towards thesecond seeking direction have not been done.
 3. The method as claimed inclaim 2, further comprising a step of determining F_(p) to be F₀ if theseeking procedure towards the second seeking direction have been done.4. The method as claimed in claim 3, further comprising a step ofresetting the step value ΔF if the first output O(F₀−ΔF) is equal to thesecond output O(F₀+ΔF).
 5. The method as claimed in claim 1, wherein themethod is used for identifying an optimal input F_(p) corresponding to aminimum output, and the first seeking direction is towards an inputcorresponding to a less output of the conclusion from the initial inputF₀.
 6. The method as claimed in claim 5, wherein F_(i) is a stop pointif F_(i) satisfies relationship of O(F_(i))<O(F_(i+1))<O(F_(i+2))< . . .<O(F_(i+n−)).
 7. The method as claimed in claim 1, wherein the method isused for identifying an optimal input F_(p) corresponding to a maximumoutput, and the first seeking direction is towards an inputcorresponding to a greater output of the conclusion from the initialinput F₀.
 8. The method as claimed in claim 7, wherein F_(i) is a stoppoint if F_(i) satisfies relationship of O(F_(i))>O(F_(i+1))>O(F_(i+2))>. . . >O(F_(i+n−1)).
 9. The method as claimed in claim 5, wherein n isequal to
 4. 10. The method as claimed in claim 1, further comprising astep of increasing i by 1 based on the conclusion.
 11. The method asclaimed in claim 1, wherein F_(p) is equal to an average of a maximumvalue and a minimum value of the certain inputs.
 12. The method asclaimed in claim 1, wherein i is integer.
 13. An information storageapparatus comprising: an processing unit for receiving parameters; aparameter-adjusting unit comprising a program for identifying optimalvalues of the parameters of the processing unit; wherein the programcomprising: codes for providing an initial input F_(i=0) to be a valueof the parameter, and detecting a corresponding initial outputO(F_(i=0)) of the processing unit; codes for determining step value ΔF;codes for providing a first input F₀−ΔF and a second input F₀+ΔF to bevalues of the parameter, and detecting a first output O(F₀−ΔF) and asecond output O(F₀+ΔF) of the processing unit; codes for determiningwhether the first output O(F₀−ΔF) is greater than the second outputO(F₀+ΔF); codes for determining a first seeking direction based on thedetermination; codes for providing other inputs F_(i), F_(i+1), F_(i+2),. . . F_(i+n−1) to be values of the parameters, and then detectingcorresponding other outputs O(F_(i)), O(F_(i+1)), O(F_(i+2)), . . .O(F_(i+n−1)); codes for determining a stop point F_(i) by comparing theoutputs O(F_(i)), O(F_(i+1)), O(F_(i+2)), . . . O(F_(i+n−1)); codes forstopping seeking along the first seeking direction at the stop point;codes for identifying an extremum output based on the detected outputs;and codes for identifying an input corresponding to the extremum outputto be the optimized value of the parameter.
 14. The information storageapparatus as claimed in claim 13, wherein the program comprising: codesfor making a determination whether seeking procedure towards a secondseeking direction being opposite to the first seeking direction from theinitial input F₀ have been done if F₀ is a stop point; and codes forresetting i to a value of zero, and seeking along the second seekingdirection if the seeking procedure towards the second seeking directionhave not been done.
 15. The information storage apparatus as claimed inclaim 14, wherein the program comprising codes for determining F_(p) tobe F₀ if the seeking procedure towards the second seeking direction havebeen done.
 16. The information storage apparatus as claimed in claim 15,wherein the program comprising codes for resetting the step value ΔF ifthe first output O(F₀−ΔF) is equal to the second output O(F₀+ΔF).